The invention relates to a method and a transmitter for providing a data stream and to a method and a receiver for retrieving at least one data segment of a data stream.
For distributing large volumes of data within a broadcasting context as in of case of, for instance, IP-TV (IP—Internet Protocol), the following two systems are currently known:
Broadcasting is in the case of a first system effected with the aid of a central infrastructure. A data stream requiring to be distributed is therein transmitted by a broadcaster to a multimedia server that has a network link to one or more users and is responsible for distributing the data stream to said users. Distributing is provided by, for example, point-to-point connections. If there are a large number of users it is possible to employ a hierarchy of multimedia servers that reduce a load for distributing one multimedia server's data stream. Core-network loading can furthermore be reduced by employing a plurality of multimedia servers because each multimedia server will exclusively serve one network segment. That system, however, requires a central infrastructure that controls distributing of the data stream to the multimedia server(s).
A second system employs overlay structures having distribution trees that manage without a central infrastructure. What are known are, for example, methods for relaying over P2P networks (P2P—peer-to-peer) such as, for instance, a PeerCast technology. Novel approaches to said second system split the data stream into partial streams that are then distributed over overlay structures such as in the case of, for instance, the known splitstream method [1] M. Castro et al, “Splitstream: High-Bandwidth Multicast in Cooperative Environments”, SOSP 2003, Oct. 19-22, 2003, Bolton Landing, N.Y., USA. The result is that all nodes can be internal nodes in one of the distribution trees and will hence contribute bandwidth for distributing the data stream. What, though, is disadvantageous about said methods is that substantial effort is needed to maintain the distribution trees. So any such method will be highly complex and very prone to faults owing to decentralized administering of the tree structures.